Conventional ultrasonic flow rate measurement devices are generally configured as follows: An inflow and outflow ports for gases are disposed in the top face of a flowmeter in order to install the device by hanging from piping, or an inflow and outflow ports of a flowmeter are coupled with straight piping. In particular, the flowmeter for use in such as a gas meter is configured as follows: The inflow and outflow ports are coupled with each other via a U-shaped and cylindrical gas-flow path member that is disposed in the inside of the gas meter, and a measuring tube for measuring a gas flow velocity is disposed in the gas-flow path member (see Patent Literature 1, for example).
FIG. 7 is a cross-sectional view of a conventional ultrasonic gas meter.
As shown in FIG. 7, inflow port 115 and outflow port 117 for gases are disposed in the top face of gas meter 116 that is formed in a rectangular box shape. The gas meter is configured such that inflow port 115 and outflow port 117 are coupled with each other via gas-flow path member 119 that is formed to be cylindrical and U-shaped.
In bottom face part 120 of the U-shaped flow path, measurement flow path 101 is disposed which measures a flow rate of a gas based on a propagation time of an ultrasonic wave. Measurement flow path 101 is equipped with ultrasonic vibrator 102 in the upstream side and ultrasonic vibrator 103 in the downstream side, with the vibrators facing each other.
Conventionally, however, it is necessary to modify the shape of the measurement flow path, the coupling configuration of the ultrasonic vibrators and a measurement circuit, and the like, depending on the piping with which the flowmeter is coupled, installation sites, applications, and the like. This has been a problem that additional time and costs are needed for development of secured measurement accuracy, resulting in inefficiency.    Patent Literature 1: Japanese Patent Unexamined Publication No. 2009-186430